The Clinical Core of the Program Project Grant will perform the cognitive and clinical assessments of allsubjects for the program project grant (PPG). The Clinical Core will identify and assess normal subjects,subjects with mild cognitive impairment (MCI), patients at appropriate stages of Alzheimer's disease (mild, moderate and severe, according to level of Mini Mental State Examination score), and patients with Parkinson's Disease, Dementia of Parkinson's Disease, and Dementia with Lewy Bodies. These cases will be referred from the Alzheimer's Disease Research Center (ADRC) at the University fo Pittsburgh and the Movement Disorders Clinics (MvtDCs) of the Pittsburgh VA Health System and the Parkinson's Center of Excellence in the Department of Neurology, University of Pittsburgh. The Core will review the study protocols with potential subjects to provide full informed consent, perform the cognitive, motor, and other assessments necessary for the protocol, and coordinate patient appointments for the imaging studies of the protocols. Follow-up appointments and ongoing telephone contacts with the subjects in the longitudinal portion of the study will be maintained by the core. The Clinical Core will coordinate with the ADRC and the MvtDCs to assure accurate and timely transfer of clinical information, cognitive scores, and other relevant data to the PPG data set, and subsequently to the Imaging/Methodology/Statistics (IMS) core for data analyses and correlation with PET and MRI data. The PPG Coordinating Committee, comprised of the PIs of the Clinical Core, the Imaging, Methodology and Statistics (IMS) Core, the PIs and CoPIs of the three projects, and the PPG Administrator, will oversee the Clinical Core. All of the investigators in this Core and all of the individuals with whom they interact to achieve the aims of the core have worked together for many years, adding to the assurance that the proposed work will be carried out appropriately.